SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '244a9a3c1a91714a182d6ab42316097d8bb8eb64e0aad167738550cde934b2d5' 
  AND token = '4/5PAFmXU8epciQz2/jYs5LyfAPMtvqb1kmd6gnRHvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}